tailieunhanh - Structural Steel Designers Handbook Part 14

Tham khảo tài liệu 'structural steel designers handbook part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | SECTION FOURTEEN FIGURE Section for brace between arch ribs. Width-Thickness Ratios 2-in top plate 7 i6-vertical plate Actual b 1 18 36 185 Allowable b 1 vja 39 45 max 158 vja 50 max The brace section is satisfactory. Rib Bracing The plan of the structural carbon steel bracing used for the arch rib is shown in Fig. . Figure shows the section used for a brace in the first panel of bracing. Rib bracing is designed to carry its own weight wind on ribs and rib bracing and an assumed buckling shear from compression of the ribs. Loads on the first-panel brace are given in Table and section properties are computed in Table . The maximum bending stress produced by total load is _ 1120 X 12 X 12 - 1284 652 ksi TABLE Loads on Brace Between Arch Ribs P kips Mx ft-kips My ft-kips Dead load . 1120 Wind . Buckling Total 1120 ARCH BRIDGES TABLE Properties of Rib Brace Axis x-x Axis y-y Section A dx Io Ad. - Ix x dy Io Ady2 Iy PL 2 47 X 3 8 . . . 6490 . . . 6 490 . 5230 5230 PL 2 24 X 7 s . . . 23 300 23 300 . 2020 . 2020 4 WT 6 X 13 35 979 1014 47 780 827 30 804 8077 Radius of gyration rx V30 804 in r. ry V8 077 in Unsupported length ft Effective length factor K truss-type member connections Slenderness ratio KL rx X X 12 Slenderness ratio KL ry X X 12 Section modulus S 30 804 24 1284 in3 Sy 8 077 652 in3 The total axial stress is fa ksi For combined stresses with wind allowable stresses may be increased 25 . Axial and bending loads are evaluated for combined stresses with Eq. with Cm 1. F ex 2 29 000 ksi F ey 2 29 000 ksi 2 . s Fa - 2 ksi Fb ksi X X X 1 - X 1 - X